EssentialsX version (/essentials): 2.0.1-b488

Server software (/version):1.12.1

EssentialsX config (if applicable):

log on server cmd:
[12:07:21 WARN]: [Essentials] Task #14 for Essentials v2.0.1-b529 generated an exception
java.lang.NullPointerException: null
at com.earth2me.essentials.xmpp.XMPPManager.updatePresence(XMPPManager.java:148) ~[?:?]
at com.earth2me.essentials.xmpp.EssentialsXMPP.updatePresence(EssentialsXMPP.java:109) ~[?:?]
at com.earth2me.essentials.xmpp.EssentialsXMPPPlayerListener$1.run(EssentialsXMPPPlayerListener.java:31) ~[?:?]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:352) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:690) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:371) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:651) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:555) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_144]
[12:07:21 WARN]: File motd.txt does not exist. Creating one for you.
[12:07:21 INFO]: 創建空的配置:F:\GAMES\MINECRAFT\connect\server_1\plugins\Essentials\userdata\c2ecbc63-ffa9-3ff8-bdfe-0e630159a8dd.yml
[12:07:52 INFO]: YumekuiiNight lost connection: Disconnected
[12:07:53 INFO]: YumekuiiNight left the game
[12:07:53 WARN]: [Essentials] Task #18 for Essentials v2.0.1-b529 generated an exception
java.lang.NullPointerException: null
at com.earth2me.essentials.xmpp.XMPPManager.updatePresence(XMPPManager.java:144) ~[?:?]
at com.earth2me.essentials.xmpp.EssentialsXMPP.updatePresence(EssentialsXMPP.java:109) ~[?:?]
at com.earth2me.essentials.xmpp.EssentialsXMPPPlayerListener$2.run(EssentialsXMPPPlayerListener.java:51) ~[?:?]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:352) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:690) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:371) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:651) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:555) [craftbukkit-1.12.1.jar:git-Bukkit-876d22c]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_144]

explain:
when i login or logout， this warning will pop up。Although it is warning not error，i'm still wondering if it will do anything to server.

Closing due to lack of response. If this is still a problem, feel free to reopen the issue.

Are you using XMPP? If not, you don't need EssentialsXXMPP.

@md678685 is correct, I've noticed that if you don't configure XMPP it causes strange errors like this. I suggest removing EssentialsXMPP if you don't know what it is/don't use it.